Range Report M118LR out of an M110 - why is my MV so much lower

[vmpglenn]

For M118LR coming out of the 20" barrel of an M110, KAC uses 2572fps as the MV value in their Bulletflight iPhone ballistics app. Conditions appear to be standard (59degF, 29.92"HG, 0' ASL).

Yet I have BH 175gr red box .308 coming out of my 20" 1:11.25 twist 416SS triple-lapped AR10T barrel at 2450fps at close to the same conditions (56degF, 30.27"HG, 900' ASL). I use a CED M2 chronograph that is about a year old.

Is my chrono off, is my AR10T barrel that much slower, or is the BH red box just loaded that much slower than M118LR? Maybe it's all three?

I would greatly appreciate any insight.

 

[TiroFijo]

Re: M118LR out of an M110 - why is my MV so much lower

Difficult to say for sure... you could try another chrono with the same rifle, and another rifle to check the velocity of the ammo.

 

[Lindy]

Re: M118LR out of an M110 - why is my MV so much lower

Black Hills 175 Match is loaded slower. It runs 2570 out of my 24" Accuracy International barrel at 70 degrees. M118LR out of that rifle runs around 2625.

 

[sinister]

Re: M118LR out of an M110 - why is my MV so much lower

It will also depend on the barrel make and type of rifling.

A Lothar Walther buttoned barrel will be slower than a cut-rifled Obermyer .298-bore barrel.